1. Field of the Invention
This invention relates to an optical connector for optical signal transmission.
2. Description of the Prior Art
An optical connector for connecting optical fibers has a plug and an adaptor. The plug has a ferrule attached to one end of an optical fiber and can be coupled to the adaptor. When the plug is connected to the adaptor, the ferrule contacts the ferrule of another plug attached to the adaptor, thereby connecting the optical fiber to the other optical fiber fastened to the other plug. A lock having screws and a lock having levers are known as devices for connecting a plug to an adaptor.
The lock with screws can firmly attach a plug to an adaptor by turning the screws. Once the plug has been attached to the adaptor, any vibration or shock applied to the plug or the optical fiber, can hardly act on the ferrule. This lock is, however, disadvantageous in that a long time is usually required to turn the screws to fasten the plug to the adaptor.
In contrast, the lock having levers is easy to use. It can attach a plug to an adaptor only by rotating or pushing the levers. The levers are rotatably coupled to both sides of the plug. Each lever has a square hole in the tip. The adaptor has projections which can fit into the square holes of the levers. After the plug has been brought into contact with the adaptor, the levers are rotated until the projections fit into the square holes, whereby the plug is connected to the adaptor. This lock has also a drawback. Since each projection fits in the square hole of the lock lever when the lever is rotated, the hole must be larger than the projection. Therefore, after the plug has been connected to the adaptor, a gap, through narrow, is left between the projection and the hole. When a force acts on the plug or the optical fiber coupled to the plug, along the axis of the ferrule, the plug inevitably move for the distance equal to this gap along the axis of the ferrule. This movement of the plug deteriorate the optical connection of the ferrule and another ferrule, though either ferrule is urged by a coil spring and stays in a "floating" condition as long as the plug is fastened to the adaptor. Further, when a force acts on the plug at right angles to the axis of the ferrule, the plug is moved in the direction the force is applied, inevitably deteriorating the optical connection between the two ferrules. In the worst case, the ferrules move away from each other for so long a distance that an optical signal fails to reach one ferrule from the other, resulting in an instantaneous interruption of optical signal communication. In short, the lock having levers is not a reliable connecting apparatus.
As has been stated, either type of a lock for connecting a plug to an adaptor has an inherent drawback. An optical connector, which can be easily operated and can reliably achieve for optical signal transmission is now greatly demanded.